Unable to manage the onboarded SSR from Mist
When you onboard an SSR with the option "Manage configuration with mist" unchecked, it will be considered only for monitoring.
User won't be able to assign a template to this SSR.
If you want to manage the SSR which was added for monitoring, the SSR needs to be released and readded again.
From Mist UI > Inventory > Select the SSR > Click on More > select release.
Once its released, readd it back by following this article.
Once the SSR appear in the Inventory page, add it to a site with the option "Manage configuration with mist" enabled. This will ensure that the SSR must be managed with mist.
If the SSR is not readded properly, you may try restarting the below service.